Plant of the Week: Plumbago (Leadwort)

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or recommend plants featured in "Plant of the Week." Please consult your local Extension
office for plants suitable for your region.

Plant of the Week

Plumbago or Leadwort Latin: Ceratostigma plumbaginoides

Keeping the ground covered with vegetation is an indisputably good thing, but we all
know plants come and go either disappearing for their season or rest or, too often,
to the great hereafter of the plant world. In sunny locations, grasses – especially
tough ones such as bermudagrass – become the default groundcover but, with a little
attention to detail other groundcovers can be used. Plumbago (Ceratostigma plumbaginoides) is one to consider.

Plumbago, or leadwort as it is often called, is a rhizomatous mat-forming perennial
from the Beijing region of China that belongs to the plumbago family. It has a woody
crown and herbaceous stems. In areas with winter temperatures below 15 degrees Fahrenheit,
the stems freeze back and new, erect stems emerge from the rhizomes in late spring
or even early summer. Plants grow 6 to 10 inches tall and will spread as wide as
conditions permit. Though the plant does spread I’ve found it to be a tentative spreader
that never has come close to being problematic by taking over neighboring plants.

Oval, shiny green, spirally arranged leaves to 2 inches long turn maroon in the fall
and present an effective display. In late summer and throughout the fall in a protracted
blooming season five petaled, three quarter inch gentian blue flowers are produced
at the ends of stems and create a good late season display. The effect is similar
to that of the spring flowering woodland phlox (Phlox divaricata).

Plumbago was probably first described to the Western garden world in 1819 when Clarke
Abel (the English gardener for whom Abelia is named) saw the plant growing in pots
in the Imperial Court in Beijing. However, its collection and description fell to
the Russian botanist Alexander von Bunge who collected and described the plant in
1833.

The common name plumbago comes from a Latin word meaning “looks like lead.” The derivation
of this common name is uncertain though it is used by both Pliny the Elder (23–79
AD) and Dioscorides (40-90 AD). The name has variously thought to have been derived
from the ability of the plant to cure lead poisoning, from the resemblance of the
flowers to the color of lead, and to the fact that a lead staining plant dye could
be made from the plant. The Latin name is from the horn-like appearance of the stigma.

Leadwort is hardy from zone 5 through 9 though in northern areas a wintertime mulch
is recommended. It makes a good addition to the rock garden or as a groundcover on
sloping sites that must fend for themselves. Don’t plant it in a situation where it
is forced to compete with vigorous grasses such as bermudagrass, for it will lose
the contest. It grows in well-drained, sunny- to medium-shade sites where it will
tolerate considerable drought. It grows in most average soils though does seem to
have an aversion to high clay content soils. Even in mild areas the foliage is often
tattered and weather-worn but the plants come through the winter in better condition
if the stems are not trimmed back until the worst part of winter has passed.

The University of Arkansas Division of Agriculture does not maintain lists of retail
outlets where these plants can be purchased. Please check your local nursery or other
retail outlets to ask about the availability of these plants for your growing area.